Pakistani intelligence officials say 20 Islamist militants were killed in an American missile attack close to the Afghan border.
The officials said 16 of the dead were Afghan militants belonging to the Haqqani network, an insurgent faction fighting the U.S. presence in Afghanistan.
The attack took place early Tuesday on a house in the North Waziristan tribal region.
The officials spoke on condition of anonymity because they were not authorized to speak to the media.
The United States relies heavily on the covert, CIA-run missile program in its efforts to kill Taliban and al-Qaida militants in Pakistan's tribal areas.
Washington does not publicly acknowledge the program, which is a source of tension between the U.S. and Pakistan. Islamabad has protested the strikes, saying they fuel militancy in the region.